Re: Fever with no symptoms
There are lots of kid viruses (by that I mean, commonly/easily caught and passed around by kids) that just cause a fever and then nothing else.
A bunch of the childhood illnesses also start with a fever for a few days, then a rash (different rashes and locations depending on the virus) when the fever breaks. These aren't really diagnosed until the rash appears, though.
For now I'd keep her home, not out in public places (no day care or play groups) and make sure she's comfortable - sometimes my kids have a higher fever but feel fine and are playing normally, but sometimes they'll have even just a low-grade fever and feel horrid. I base treatment much more on how they're feeling/acting than the # on the thermometer.